Metastatic cancer, or metastatic disease, is the spread of a cancer from one organ to another organ or another site in a subject. Metastasis is a complex series of biological steps in which cancerous cells leave an original site and migrate to another site in a subject via a number of different possible routes, such as via the bloodstream, the lymphatic system, or by direct extension.
Once a cancer has metastasized, the treatment of metastatic cancer relies on the same traditional techniques to treat primary cancer, such as radiosurgery, chemotherapy, radiation therapy and surgery, or a combination of these interventions. In many cases, however, the treatment options that are currently available are not able to cure the metastatic cancer, although metastatic testicular cancer and thyroid cancer are notable exceptions.
Metastatic cancer is also of particular concern as the incidence of some cancers, such as breast cancer or melanoma, remains high in younger people resulting in a profound effect on the number of productive years lost due to the illness.
Melanoma, for example, is a cancer that has a very high incidence and mortality rate. In some countries, melanoma is the most common type of cancer in young adults. The mean age at diagnosis of melanoma is around 50 years, which is 10-15 years earlier than the commoner diagnoses of prostate, bowel, and lung cancer. Therefore, melanoma is second only to breast cancer in the number of productive years lost.
The 15-year survival rates for localised melanoma exceed 50%, but fall to 30% when there is nodal involvement, and to less than 2% when systemic involvement is evident. Metastatic melanoma is essentially incurable, and as such treatment of melanoma places a high emphasis on preventing metastasis of the primary cancer.
Single-agent dacarbazine chemotherapy, with modest response rates of 15-20%, remains the standard of care for treatment of metastatic melanoma as no combination chemotherapy or biochemotherapy has demonstrated improved overall survival in phase III randomised controlled trials. For example, while some proposed vaccine biotherapies have targeted the immune response as a means to preventing and/or treating melanoma, none of these biotherapies produces response or survival rates higher than that of chemotherapy.
Metastatic breast cancer usually occurs several years after resection of the primary breast cancer. Metastatic breast cancer cells frequently differ from the preceding primary breast cancer in properties and may often develop resistance to several lines of previous treatment and acquired increased metastatic potential. The prognosis of metastatic breast cancer is often poor, as distant metastases are the cause of about 90% of deaths due to breast cancer.
It should also be added that an additional complication with respect to the treatment of both primary and metastatic cancers is that treatment regimes involving standard chemotherapeutic agents are known to have variable and unpredictable effects, including efficacy and the extent of undesired side effects.
Accordingly, there is a need to provide improved methods and/or products to address one or more problems in the prevention and/or treatment of metastatic cancer and/or to provide one or more advantages.